Lithographic apparatus and device manufacturing method

Abstract

A lithographic apparatus includes a base frame, an illumination system configured to condition a radiation beam and supported by the base frame, a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam, a substrate table constructed to hold a substrate, a projection system configured to project the patterned radiation beam onto a target portion of the substrate, a positioning device configured to position the substrate table, the positioning device being supported by the base frame, a sensor configured to sense a vibration caused by a torque exerted on the base frame, and an actuator configured to exert a force on the illumination system or the base frame, in response to the sensed vibration, in order to at least partly dampen the vibration.

What is claimed is: 
     
       1. A lithographic apparatus comprising:
 a base frame; 
 an illumination system configured to condition a radiation beam and supported by the base frame; 
 a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam; 
 a substrate table constructed to hold a substrate; 
 a projection system configured to project the patterned radiation beam onto a target portion of the substrate; 
 a positioning device configured to position the substrate table, the positioning device being supported by the base frame and comprising a balance mass configuration, the balance mass configuration comprising a balance mass movable relative to the substrate table and configured to receive a reaction force arising from movement of the substrate table by the positioning device; 
 a sensor configured to sense a vibration caused by a torque exerted on the base frame, the torque being caused by the balance mass configuration; and 
 an actuator configured to exert a force on the illumination system or the base frame, in response to the sensed vibration, in order to at least partly dampen the vibration. 
 
     
     
       2. The lithographic apparatus according to  claim 1 , wherein the sensor is substantially arranged in line with the force exerted by the actuator. 
     
     
       3. The lithographic apparatus according to  claim 1 , wherein the actuator and the sensor are substantially co-located. 
     
     
       4. The lithographic apparatus according to  claim 1 , wherein the actuator comprises a first member mounted to the illumination system and a second member that is freely suspended and configured as a reaction mass. 
     
     
       5. The lithographic apparatus according to  claim 4 , wherein the first member of the actuator is mounted to the illumination system via an interface mass and a damping member. 
     
     
       6. The lithographic apparatus according to  claim 1 , comprising a plurality of sensors configured to sense the vibration and a respective plurality of actuators configured to exert a force on the illumination system or base frame in response to the sensed vibration. 
     
     
       7. The lithographic apparatus according to  claim 1 , wherein the balance mass of the balance mass configuration is configured as a reaction mass of the actuator. 
     
     
       8. The lithographic apparatus according to  claim 7 , wherein the balance mass comprises a magnet plate of the positioning device, the magnet plate comprising a two-dimensional pattern of permanent magnets. 
     
     
       9. The lithographic apparatus according to  claim 7 , wherein the balance mass comprises a coil assembly of the positioning device, the coil assembly comprising a two-dimensional pattern of coils. 
     
     
       10. The lithographic apparatus according to  claim 7 , wherein the actuator comprises a first actuator configured to exert a force in a first horizontal direction and a second actuator configured to exert a force in a second horizontal direction, the second horizontal direction being substantially perpendicular to the first horizontal direction. 
     
     
       11. The lithographic apparatus according to  claim 1 , comprising a further positioning device configured to position the support, the further positioning device having a further balance mass configuration, and wherein a balance mass of the further balance mass configuration is configured as a reaction mass of the actuator. 
     
     
       12. The lithographic apparatus according to  claim 1 , wherein the sensor is configured to sense vibrations caused by the torque, in a range of 5 to 30 Hz. 
     
     
       13. The lithographic apparatus according to  claim 1 , wherein the actuator comprises an electromagnetic actuator. 
     
     
       14. The lithographic apparatus according to  claim 1 , further comprising a controller configured to receive a sensor signal from the sensor, process the sensor signal to derive an actuator control signal and output the actuator control signal to control the actuator. 
     
     
       15. The lithographic apparatus according to  claim 14 , wherein a control loop of the controller comprises a filter to improve a stability of the control loop. 
     
     
       16. A device manufacturing method comprising:
 conditioning a radiation beam using an illumination system that is supported by a base frame; 
 imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam using a patterning device; 
 projecting the patterned radiation beam onto a target portion of a substrate; 
 positioning a substrate table holding the substrate using a positioning device supported by the base frame; 
 receiving at least part of a reaction force arising from the positioning of the substrate table by a balance mass of a balance mass configuration, the balance mass movable relative to the substrate table; 
 sensing a vibration caused by a torque exerted on the base frame, the torque is being caused by the balance mass configuration of the positioning device; and 
 exerting a force, using an actuator, on the illumination system or the base frame, in response to the sensed vibration, in order to at least partly dampen the vibration. 
 
     
     
       17. The method of  claim 16 , wherein the sensor is substantially arranged in line with the force exerted by the actuator. 
     
     
       18. The method of  claim 16 , wherein the actuator comprises a first member mounted to the illumination system and a second member that is freely suspended and configured as a reaction mass. 
     
     
       19. The method of  claim 16 , wherein the actuator comprises a first member mounted to the illumination system and further comprising absorbing a reaction force of the actuator using a second member that is freely suspended and configured as a reaction mass. 
     
     
       20. The method of  claim 16 , wherein the balance mass of the balance mass configuration is configured as a reaction mass of the actuator.